Merge remote-tracking branch 'remotes/borntraeger/tags/s390x-20170201' into staging

s390x fixes

- build error with old gcc versions
- race between cmma reset and rom/loader resets
- linux-user vs. cpu model

# gpg: Signature made Wed 01 Feb 2017 08:24:47 GMT
# gpg:                using RSA key 0x117BBC80B5A61C7C
# gpg: Good signature from "Christian Borntraeger (IBM) <borntraeger@de.ibm.com>"
# Primary key fingerprint: F922 9381 A334 08F9 DBAB  FBCA 117B BC80 B5A6 1C7C

* remotes/borntraeger/tags/s390x-20170201:
  target/s390x: use "qemu" cpu model in user mode
  s390x/kvm: fix small race reboot vs. cmma
  s390-pci: fix compilation on older GCC versions

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>